The words blend, blende sound the same but have different meanings and spellings. Why do blend, blende sound the same even though they are completely different words?
The answer is simple: blend, blende are homophones of the English language.
The act of blending.
To combine or mix so that the constituent parts are indistinguishable from one another: "He has no difficulty blending his two writing careers: novels and films” ( Charles E. Claffey).
To combine (varieties or grades) to obtain a mixture of a particular character, quality, or consistency: blend tobaccos.
To form a uniform mixture: "The smoke blended easily into the odor of the other fumes” ( Norman Mailer).
Any of various shiny minerals composed chiefly of metallic sulfides.
Definitions from The American Heritage® Dictionary of the English Language, 4th Edition and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.